This double-blind, randomized placebo-controlled study has recruited 253 children from birth. These babies, with a family history of atopic disease, will be randomly assigned into one of 2 groups to receive either normal infant formula or formula with Bifidobacterium longum and Lactobacillus rhamnosus GG. The formula will be consumed postnatally for 6 months, after which the child will continue with normal follow-on milk. Children will be examined at the neonatal period and at 1, 3, 6, 12 and 24 months. Blood samples will be collected at birth (cord blood) and at 1 year of age. Blood will be analyzed for cytokines, total IgE and specific IgE. Skin prick test for common allergens will also be performed at 1 year of age. Stools will be collected at 5 days, 1, 3, 12 months and analyzed for the pattern of stool colonization.